Pipe cutter

ABSTRACT

A power tool includes a pipe holder, a knife pivotally coupled to the pipe holder, and a drive mechanism coupled to at least one of the pipe holder and the knife. The knife includes a cutting edge having a first portion, a second portion, and an included angle, such as an obtuse angle, between the first portion and the second portion. The first portion of the cutting edge has a first length, and the second portion of the cutting edge has a second length. The drive mechanism is operable to move the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife. The power tool also includes a motor coupled to the drive mechanism and a power supply electrically coupled to the motor to selectively power the motor for operating the drive mechanism.

RELATED APPLICATIONS

This application is a continuation-in-part of International Application PCT/US2008/069188, filed Jul. 3, 2008, and International Application PCT/US2008/069189, also filed Jul. 3, 2008, both of which claim priority to U.S. Provisional Patent Application No. 60/947,706, filed Jul. 3, 2007, the entire contents of which are all hereby incorporated by reference.

BACKGROUND

The present invention generally relates to power tools and, more specifically, to battery-powered pipe cutters.

Manually-operated pipe cutters perform cutting operations in various ways, such as with sawing motions or by successive ratcheting of a pipe cutter knife through a pipe. Oftentimes, these methods of pipe cutting result in imperfect cuts or, when cutting a pipe of a material such as PVC, snapping of the pipe. Manually-operated pipe cutters also cause ergonomic difficulties for the user. In particular, a user having a relatively small hand size or low hand or wrist strength may experience difficulty completing a pipe cut. Additionally, the use of manually-operated pipe cutters can be time consuming.

SUMMARY

In one embodiment, the invention provides a power tool including a pipe holder, a knife pivotally coupled to the pipe holder, and a drive mechanism coupled to at least one of the pipe holder and the knife. The knife includes a cutting edge having a first portion, a second portion, and an included angle between the first portion and the second portion. The first portion of the cutting edge has a first length, and the second portion of the cutting edge has a second length. The angle is, for example, an obtuse angle having a value between approximately 135° and approximately 165°. The drive mechanism is operable to move the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife. The power tool also includes a motor coupled to the drive mechanism and a power supply electrically coupled to the motor to selectively power the motor for operating the drive mechanism.

In another embodiment, the invention provides a power tool including a housing assembly supporting a motor and a drive mechanism and a pipe holder coupled to the housing assembly. The pipe holder is configured to support a pipe. The power tool also includes a knife pivotally coupled to the pipe holder and a battery coupled to the housing assembly. The knife includes a cutting edge having a first portion, a second portion, and an included angle between the first portion and the second portion. The first portion of the cutting edge has a first length, and the second portion of the cutting edge has a second length. The angle is, for example, an obtuse angle having a value between approximately 135° and approximately 165°. The battery is electrically coupled to the motor to selectively power the motor to drive the drive mechanism. The drive mechanism is operable to move the knife relative to the pipe holder to cut the pipe supported by the pipe holder.

In yet another embodiment, the invention provides a pipe cutter including a housing assembly, a pipe holder coupled to the housing assembly, and a knife pivotally coupled to the pipe holder. The knife includes a cutting edge having a first portion, a second portion, and an included angle between the first portion and the second portion. The first portion of the cutting edge has a first length, and the second portion of the cutting edge has a second length. The angle is, for example, an obtuse angle having a value between approximately 135° and approximately 165°. The knife and the pipe holder define a slot therebetween for receiving a pipe. The pipe cutter also includes a drive mechanism positioned at least partially within the housing assembly and coupled to at least one of the pipe holder and the knife. The drive mechanism is operable to move the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife to cut the pipe positioned within the slot. The pipe cutter further includes a motor positioned at least partially within the housing assembly and coupled to the drive mechanism and a battery pack removably coupled to the housing assembly. The battery pack is electrically coupled to the motor to selectively power the motor to operate the drive mechanism for moving the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife.

In still another embodiment, the invention provides a power tool that includes a pipe holder, a knife, and a drive mechanism. The knife is pivotally coupled to the pipe holder, and includes a cutting edge having a first portion and a second portion. The first portion of the cutting edge and the second portion of the cutting edge are oblique with respect to one another, and the first portion of the cutting edge has a first length and the second portion of the cutting edge has a second length. The drive mechanism is coupled to at least one of the pipe holder and the knife, and is operable to move the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife. A motor is coupled to the drive mechanism, and a power supply is electrically coupled to the motor to selectively power the motor for operating the drive mechanism.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a piper cutter according to one embodiment of the invention.

FIG. 1B is a perspective view of a pipe cutter according to another embodiment of the invention.

FIG. 2 is a perspective view of a pipe cutter according to yet another embodiment of the invention.

FIG. 3 is a perspective view of the pipe cutter shown in FIG. 2 with housing portions of the pipe cutter removed to illustrate internal gear mechanisms.

FIG. 4 is a perspective view of a portion of the pipe cutter shown in FIG. 2 with housing portions of the pipe cutter removed to illustrate internal gear mechanisms.

FIG. 5 is another perspective view of the portion of the pipe cutter shown in FIG. 4.

FIG. 6 is a perspective view of a bevel gear with a spline for use in the pipe cutter shown in FIG. 2.

FIG. 7 is an exploded perspective view of a portion of a pipe cutter according to yet another embodiment of the invention.

FIG. 8 is a cross-sectional view of the portion of the pipe cutter shown in FIG. 7.

FIG. 9 is a perspective view of a portion of a pipe cutter according to still another embodiment of the invention.

FIG. 10 is a side view of the portion of the piper cutter shown in FIG. 9.

FIG. 11 is an end view of the portion of the pipe cutter shown in FIG. 9.

FIG. 12 is a top view of the portion of the pipe cutter shown in FIG. 9.

FIG. 13 illustrates a battery pack for use with a variety of power tools.

FIG. 14 illustrates a knife according to one embodiment of the invention.

FIG. 15 illustrates a knife according to another embodiment of the invention.

FIG. 16 illustrates a knife according to yet another embodiment of the invention.

FIG. 17 illustrates a knife according to still another embodiment of the invention.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION

FIG. 1A illustrates a power tool 10 according to one embodiment of the invention. In the illustrated embodiment, the power tool 10 is a pipe cutter operable to cut a variety of pipes. For example, the illustrated pipe cutter 10 can cut a pipe having a 2 inch inner diameter or less. In other embodiments, the pipe cutter 10 may be configured to cut a pipe having a diameter greater than 2 inch. In addition, the illustrated pipe cutter 10 is adapted to cut a polyvinyl chloride (PVC) pipe, although a variety of different types of pipes, such as, for example, other types of plastic pipes, metal pipes, or the like, may also be cut with the pipe cutter 10.

The pipe cutter 10 includes a housing assembly 14, a motor and a drive mechanism (FIG. 2) positioned within the housing assembly 14, and a cutting mechanism 18 coupled to a forward portion 22 of the housing assembly 14. The cutting mechanism 18 includes a pipe holder 26 and a knife 30 defining a slot 34 therebetween. The slot 34 is configured to receive a pipe to be cut by the cutting mechanism 18. The knife 30 is coupled to the motor through the drive mechanism so that operation of the motor moves the knife 30 toward the pipe holder 26 to cut the pipe. As described below with respect to FIGS. 14-17, other embodiments of the knife 30 include an angled blade to reduce pipe deformation caused by the knife as the knife cuts the pipe.

The illustrated pipe cutter 10 also includes a battery pack 38 electrically coupled to the motor such that the pipe cutter 10 is a hand-held, battery-operated power tool. In the illustrated embodiment, the battery pack 38 is a 12-volt power tool battery pack and includes three (3) Lithium-ion battery cells. In other embodiments, the battery pack 38 may include fewer or more battery cells such that the battery pack 38 is a 14.4-volt power tool battery pack, an 18-volt power tool battery pack, or the like. Additionally or alternatively, the battery cells may have chemistries other than Lithium-ion such as, for example, Nickel Cadmium, Nickel Metal-Hydride, or the like. In still other embodiments, the pipe cutter 10 may be a corded power tool.

The battery pack 38, or other power supply, connects to a rearward, or handle, portion 42 of the housing assembly 14 and selectively provides power (e.g., electricity) to the motor to drive the drive mechanism and, thereby, pivot the knife 30. In the illustrated embodiment, the battery pack 38 is partially insertable into the handle portion 42 of the housing assembly 14 to electrically couple to the motor, but may alternatively be coupled to the handle portion 42 by, for example, sliding, snapping, rotating, or the like. An LED fuel gauge (not shown) is included on the pipe cutter 10, the battery pack 38, or both to provide an indication to a user of the energy level of the battery pack 38.

As shown in FIG. 13, the battery pack 38 is usable with other power tools in addition to the pipe cutter 10. For example, in the illustrated embodiment, the battery pack 38 is also usable with a driver drill 400, a micro-inspection camera 410, a PVC pipe cutter with a wire cutting mechanism 420, an impact driver 430, and a metal pipe cutter 440. Furthermore, the battery pack 38 may be used with other power tools not specifically discussed herein.

FIG. 1B illustrates a pipe cutter 10B according to another embodiment of the invention. The illustrated pipe cutter 10B is substantially similar to the pipe cutter 10 shown in FIG. 1A, and like parts have been given the same reference numerals plus a “B” annotation. In the illustrated embodiment, the pipe cutter 10B includes an 18-volt power tool battery pack 38B connected to a handle portion 42B of a housing assembly 14B. The battery pack 38B includes five (5) Lithium-ion battery cells and is coupled to the handle portion 42B by sliding. Similar to the battery pack 38 discussed above, the battery pack 38B may alternatively include fewer or more battery cells, the battery cells may have chemistries other than Lithium-ion, and/or the battery pack 38B may be coupled to the handle portion 42B using other coupling means.

In some embodiments, the pipe cutters 10, 10B may include drive mechanisms configured to quickly return the knives 30, 30B of the pipe cutters 10, 10B to an open position. For example, the pipe cutters 10, 10B may include one of the drive mechanisms illustrated and described in International Patent Application Publication No. WO2009/006588, entitled “PIPE CUTTER”, filed Jul. 3, 2008, the entire contents of which is hereby incorporated by reference.

FIGS. 2-5 illustrate a pipe cutter 110 according to another embodiment of the invention. Similar to the pipe cutters 10, 10B shown in FIGS. 1A and 1B, the illustrated pipe cutter 110 is a hand-held, battery-operated power tool. As such, like parts have been given the same reference numerals plus 100. In addition, the features, and alternatives to the features, of the pipe cutter 110 described below may be used in the pipe cutters 10, 10B shown in FIGS. 1A and 1B.

The illustrated pipe cutter 110 includes an internal casing 116 positioned within the forward portion 22 and the handle portion 42 of the housing assembly 14 shown in FIGS. 1A and 1B. The internal casing 116 may be composed of a hard plastic material, a metal material, and/or any other material or combination of materials suitable for housing the various components of the pipe cutter 110. The casing 116 houses or supports various mechanical and/or electrical components of the pipe cutter 110 configured for conducting the cutting function of the pipe cutter 110.

In the illustrated embodiment, the handle portion of the housing assembly supports a battery 138, a motor 146, and a drive mechanism 150 (FIG. 3). The pipe cutter 110 is operable to receive power from the battery 138. According to another embodiment, the pipe cutter 110 may be powered by alternating current (AC) power provided via a corded plug electrically coupled to a wall outlet or any number of suitable powering options.

The battery 138, or power supply, is removably coupled to the handle portion to provide power to the motor 146. In the illustrated embodiment, the battery 138 extends from a rearward end of the handle portion when coupled to the pipe cutter 110. The battery 138 may be coupled to the pipe cutter 110 via any number of suitable means, such as insertion, sliding, snapping, rotating, or other coupling activities. In other embodiments, the battery 138 may be a dedicated battery contained (e.g., partially or entirely housed) within the pipe cutter 110. When coupled to the handle portion, the battery 138 provides power directly to the motor 146 or may power the motor 146 through a control circuit (not shown). The control circuit controls various aspects of the pipe cutter 110, the motor 146, and/or the battery 138 and may also monitor operation of the pipe cutter 110 and its components.

As shown in FIG. 3, the drive mechanism 150 includes a drive assembly 154 and a cutting gear assembly 158. The drive assembly 154 is supported by the handle portion of the pipe cutter 110 and is powered by the motor 146 to drive the cutting gear assembly 158. In the illustrated embodiment, the drive assembly 154 includes a four-stage planetary gear reduction 162. In other embodiments, the drive assembly 154 may include different gear reductions. In yet another embodiment, the drive assembly 154 may include another type of gear configuration suitable to drive the cutting operation of the pipe cutter 110.

In the illustrated embodiment, the casing 116 supports the cutting gear assembly 158, a knife 130, and a pipe holder 126. The cutting gear assembly 158 is driven by the drive assembly 154 and operates to control cutting motion of the knife 130, which performs the cutting action of the pipe cutter 110. The knife 130 includes a blade 166 and is pivotally movable relative to the housing assembly 14 (FIGS. 1A and 1B), the casing 116, and the pipe holder 126. The illustrated embodiment of the blade 166 straight along its blade 166. Other embodiments of knives that may be used in the pipe cutter 110 are described below with respect to FIGS. 14-17. The knife 130 is formed from a hardened metal material suitable to cut pipes of various materials and of a size sufficient to cut through a desired pipe size. Together, the knife 130 and the pipe holder 126 define a slot 134 for receiving a pipe to be cut. The pipe holder 126, which is stationary relative to the housing assembly 14, is formed with a curved surface 170 facing the blade 166 of the knife 130. The curved surface 170 of the pipe holder 126 provides support for a pipe during the cutting action and helps to align the pipe to be cut. The pipe holder 126 may be integrally formed with the housing assembly 14 or may be separately coupled to the forward portion 22 of the housing assembly 14. The pipe holder 126 is formed from a hard plastic material, a metal material, and/or any other material or combination of materials suitable for supporting a pipe during the cutting activity.

In the illustrated embodiment, the pipe holder 126 includes a cover 174 that forms an exterior portion of the pipe cutter 110 and houses various mechanical and/or electrical components of the pipe cutter 110. The cover 174 may be integrally formed with the housing assembly 14, may be removably coupled to the forward portion 22, or may be permanently coupled to the forward portion 22. The cover 174 may be formed from a hard plastic material, a metal material, and/or any other material or combination of materials suitable for housing the various components of the pipe cutter 110. In the illustrated embodiment, the cover 174 is coupled to the forward portion 22 of the housing assembly 14 and the pipe holder 126. The portion of the cover 174 that is coupled to the holder 126 is formed with a curved surface of the same shape as the curved surface 170 of the pipe holder 126 such that the pipe holder 126 and the cover 174 cooperate to support a pipe during the cutting motion.

The cutting gear assembly 158 is coupled to and driven by the drive assembly 154 to pivot the knife 130 of the pipe cutter 110. The cutting gear assembly 158 may include various numbers of gears in various configurations. Referring to FIGS. 3-5, the cutting gear assembly 158 includes a first gear 178 driven by the drive assembly 154 and a second gear 182, whereby the first gear 178 engages and drives the second gear 182. In the illustrated embodiment, the first gear 178 and the second gear 182 are bevel gears, although in further embodiments, the first and second gears 178, 182 may be other types of gears.

The second gear 182 includes a spline 186 (also shown in FIG. 6), or spur gear, that extends outward from a rear face 190 of the second gear 182. The spline 186 may be integrally formed with the second gear 182 or may be separately coupled to the second gear 182. The spline 186 includes a toothed portion 194 and a non-toothed portion 198. The spline 186 may include teeth formed on less than half of the circumference of the spline 186. In the illustrated embodiment, the teeth are formed on approximately 90° of the spline 186 circumference, which will result in the knife 130 pivoting 90° during the cutting motion, as discussed below. In embodiments in which the knife 130 pivots less than 90°, the teeth are formed on less than 90° of the spline 186 circumference. Alternatively, in embodiments in which the knife 130 pivots more than 90°, the teeth are formed on more than 90° of the spline circumference.

The cutting gear assembly 158 includes a third gear 202, which is a driven gear that causes the cutting motion of the knife 130. In the illustrated embodiment, the third gear 202 intermeshes with and is driven by the toothed portion 194 of the spline 186; however, the non-toothed portion 198 of the spline 186 does not engage the third gear 202.

Referring to FIGS. 2-5, one end of the knife 130 is rotatably coupled to the third gear 202 at a pivot point defined by a gear shaft 206. The knife 130 is normally biased upward and away from the pipe holder 126 to a first position for receiving a pipe within the slot 134. A spring 210 (FIGS. 3 and 5) extends between the knife 130 and the pipe holder 126 to bias the knife 130 to the first position. In the illustrated embodiment, the spring 210 is an extension spring attached to the internal casing 116 at one end and to the knife 130 at an opposite end. As the third gear 202 rotates, the knife 130 pivots about the pivot point toward the pipe holder 126. The degree that the knife 130 pivots corresponds with the angular distance of the toothed portion 194 of the spline 186. In the illustrated embodiment, the cover 174 encloses an interior area of the pipe holder 126, which contains the spring 210 and the pivot point.

In a further embodiment, the spline 186 is fully toothed (e.g., a full spur gear) and the knife 130 may be returned to the initial position, or the first position, by other means than the spring, such as by reversing the motor 146.

During operation of the pipe cutter 110, a user positions a pipe in the slot 134 such that the pipe rests on the curved surface 170 of pipe holder 126. A user electrically couples the power supply 138 to the motor 146 (e.g., by actuating a switch assembly or circuit) to power the motor 146 and, thereby, drive the drive assembly 154. The drive assembly 154 intermeshes with and drives the first gear 178 of the cutting gear assembly 158, which rotates the second gear 182. As the second gear rotates 182, the spline 186 also rotates. When the toothed portion 194 of the spline 186 engages the third gear 202, the third gear 202 rotates to pivot the knife 130.

As the third gear 202 rotates, the knife 130 pivots toward the pipe holder 126 such that the blade 166 of the knife 130 cuts through a pipe (not shown) positioned in the slot 134. The pivot range of the knife 130 corresponds to the arc length of the toothed portion 194 on the spline 186. In the illustrated embodiment, after the toothed portion 194 of the spline 186 rotates past the third gear 202, the knife 130 will have completed the pipe cut and cutting motion. When the non-toothed portion 198 of the spline 186 is adjacent to the third gear 202, the spline 186 and the third gear 202 do not engage such that the spring 210 (FIGS. 3 and 5) biases the knife 130 away from the pipe holder 126 to the first position. The knife 130 is then in position for the next cutting operation.

FIGS. 7 and 8 illustrate another embodiment of a drive mechanism 214 for use with the pipe cutters 10, 10B, 110 of FIGS. 1A-5. The drive mechanism 214 includes the drive assembly 154 shown in FIG. 3, but includes another gear assembly 218 to pivot the knife 130 relative to the pipe holder 126. The illustrated gear assembly 218 includes a first gear 222 driven by the drive assembly 154 and a second gear 226, whereby the first gear 222 engages and drives the second gear 226. In the illustrated embodiment, the first gear 222 and the second gear 226 are bevel gears, although in further embodiments, the first and second gears 222, 226 may be other types of gears.

As shown in FIGS. 7 and 8, the second gear 226 includes an elongated shaft 230 having a spline 234. The elongated shaft 230 extends axially outward from the second gear 226 through the knife 130. Bearings 238, 242 are positioned about opposite ends of the shaft 230 to support and guide the shaft 230 during rotation.

The gear assembly 218 also includes a planetary gear reduction 246. The planetary gear reduction 246 is positioned about the elongated shaft 230 and includes four planetary gears 250, a ring gear 254, and a driven gear 258. The spline 234 engages the planetary gears 250 such that, as the second gear 226 is rotated, the planetary gears 250 move about the shaft 230 within the ring gear 254. The driven, or output, gear 258 is coupled to the planetary gears via short rods 262 (FIG. 8) such that the driven gear 258 rotates as the planetary gears 250 move within the ring gear 254. The driven gear 258 also engages the knife 130 to output rotation of the second gear 226 to the knife 130 at a reduced speed. In some embodiments, the four-stage planetary gear reduction 162 of the drive assembly 154 may be omitted or modified since the planetary gear reduction 246 in the gear assembly 218 also reduces the speed of rotation from the motor 146.

As shown in FIG. 7, the drive mechanism 218 includes a lock key 266 and a key release button 270. The lock key 266 is biased by a spring 274 to engage the ring gear 254 to prevent rotation of the ring gear 254 relative to the pipe holder 126. In this position, the planetary gear reduction 246 transmits rotation of the second gear 226 to the knife 130. The key release button 270, or actuator, is positioned adjacent to the lock key 266 and extends partially out of the pipe holder 126. A spring 278 biases the button 270 slightly apart from the lock key 266 such that the button 270 does not disengage the lock key 266 from the ring gear 254. When the key release button 270 is depressed by a user against the bias of the spring 278, the button 270 lifts the lock key 266 out of engagement with the ring gear 254. In this position, the ring gear 254 can rotate relative to the pipe holder 126 such that rotation of the second gear 226 is not transmitted to the knife 130, and rotation of the knife 130 is not transmitted to the second gear 226. The user can thereby manually pivot the knife 130 away from the pipe holder 126 without having to reverse the motor 146.

The drive mechanism 218 also includes a size switch 282 coupled to the pipe holder 126. The size switch 282 allows a user to limit the size of the slot 134 (FIG. 2) by only allowing the knife 130 to pivot apart from the pipe holder 126 at set increments. In the illustrated embodiment, the size switch 282 includes a pin 286 extending through a curved slot 290 in the pipe holder 126. The pin 286 engages a stepped surface 294 formed on the knife 130 to limit the pivot range of the knife 130 relative to the pipe holder 126. In the illustrated embodiment, the stepped surface 294 of the knife 130 includes three steps such that the user can limit the size of the slot 134 to one of three sizes. In other embodiments, the stepped surface 294 can include fewer or more steps to limit the size of the slot 134 to larger and/or smaller sizes, or the stepped surface 294 may be formed to allow for continuous resizing of the slot 134.

FIGS. 9-12 illustrate a portion of a pipe cutter 310 according to yet another embodiment of the invention. Similar to the pipe cutters 10, 10B shown in FIGS. 1A and 1B, the illustrated pipe cutter 310 is a hand-held, battery-operated power tool. As such, like parts have been given the same reference numerals plus 300. In addition, the features, and alternatives to the features, of the pipe cutter 310 described below may be used in the pipe cutters 10, 10B shown FIGS. 1A and 1B.

Similar to the previous embodiments, the pipe cutter 310 includes a knife 330, a pipe holder 326, and a drive mechanism 350. The illustrated drive mechanism 350 includes a screw 354, a coupling block 358, and a pair of links 362, 366. The screw 354 is formed as an elongated threaded rod and is rotatably driven in a forward and/or a reverse direction by a drive assembly (not shown). In some embodiments, the drive assembly may be, for example, a dedicated drive assembly of an existing power tool or the drive assembly 154 discussed with reference to FIGS. 2-8.

The screw 354 extends, and is rotatably movable, through a threaded hole in the coupling block 358. The coupling block 358 is pivotally coupled to a rear portion 370, 374 of each of the links 362, 366, which extend outward from and on opposite sides of a driven end of the screw 354. Forward ends 378, 382 of the links 362, 366 are coupled to the knife 330 and the pipe holder 326, respectively, to pivotally move the knife 330 and the pipe holder 326 toward and away from each other.

The knife 330 is configured to perform the cutting action of the pipe cutter 310, and the pipe holder 326 provides support for a pipe, P, to be cut. Together, the knife 330 and the pipe holder 326 define a slot 334 to receive the pipe, P, to be cut. As shown in FIGS. 9 and 10, the knife 330 and the pipe holder 326 are pivotally coupled together at a pivot point 386 defined by a generally U-shaped bracket 390. The illustrated bracket 390 is coupled to the knife 330 and the pipe holder 326 and is coupled to a forward end of the screw 354 such that the screw 354 rotates within the bracket 390 when driven.

During operation of the piper cutter 310, a user positions the pipe, P, in the slot 334 between the pipe holder 330 and the knife 326. The user activates the drive mechanism 350 (e.g., with a power supply and a motor) to rotate the screw 354 and drive the coupling block 358. Rotating the screw 354 in the forward direction drives the coupling block 358 and the rear portions 370, 374 of the links 362, 366 toward the forward end of the screw 354 (i.e., toward the bracket 390). As the links 362, 366 move forward, the forward ends 378, 382 of the links 362, 366 pivot away from each other, pushing the knife 330 and the pipe holder 326, respectively. The knife 330 and the pipe holder 326 thereby pivot about the pivot point 386 toward one another to cut the pipe, P, with the knife 330.

Rotating the screw 354 in the reverse direction drives the coupling block 358 and the rear portions 370, 374 of the links 362, 366 away from the forward end of the screw 354 (i.e., away from the bracket 390). As the links 362, 366 move backward, the forward ends 378, 382 of the links 362, 366 pivot toward each other, pulling the knife 330 and the pipe holder 326, respectively. The knife 330 and the pipe holder 326 thereby pivot about the pivot point 386 away from one another to enlarge the slot 334 defined between the knife 330 and the pipe holder 326.

The pipe cutters and knives described above include blades having a single, straight blade. Although such a blade is able to adequately cut pipes during normal operating conditions, under more extreme operating conditions, such as a low-temperature condition (e.g., below approximately 5° C.), a knife having a straight cutting blade may crack the pipe due to the torque generated by the pipe cutter, the deformation of the pipe caused by the pipe cutter, and the rigidity of the cold pipe. In some embodiments, the pipe cutter's blade is angled to provide a burr-free cut with minimal deformation of the pipe, under both normal operating conditions and low-temperature conditions. For example, instead of the pipe cutter having a knife with a straight blade as shown and described above, a knife with an angled blade is used to increase the force applied to a single point or area of the pipe. The increased force facilities the splitting of the pipe, and enables the pipe cutter to be used during low-temperature conditions without cracking the pipe.

For descriptive purposes, a straight blade is considered to have a blade angle of 180°, that is, the knife has a linear cutting edge or blade as shown in FIGS. 1A, 1B, 2, 7, and 9. As the angle is reduced (i.e., approaches zero or is made sharper), the deformation of the pipe the blade causes during a cut is reduced, and the time required to split the pipe is correspondingly reduced. If the blade angle becomes too sharp, the time required to cut the pipe can increase, or the pipe cutter may require a blade that is unreasonably large. Therefore, although adding an angled blade reduces the deformation caused during the cut and the time required to split the pipe, a balance must be struck between the angle of the blade, the deformation caused by the cut, and the time required to completely cut the pipe. In a preferred embodiment, the blade angle is an obtuse angle and is between approximately 125° and approximately 165° to achieve varying degrees of reduced cutting time, reduced pipe deformation, and an increased ability to cut pipes during low-temperature conditions.

FIG. 14 illustrates one embodiment of a knife 500 having an angled blade or cutting edge 502. The blade 502 has a first edge portion 504 and a second edge portion 506. The first edge portion 504 has a length L₁, and the second edge portion 506 has a length L₂. In the illustrated embodiment, the length L₁ of the first edge portion 504 is greater than the length L₂ of the second edge portion 506. In other embodiments, the first edge portion 504 and the second edge portion 506 have the same length, or the length L₂ of the second edge portion 506 is greater than the length L₁ of the first edge portion 504. The first edge portion 504 and the second edge portion 506 are oblique with respect to one another, or have an included blade angle 508 between them. In the illustrated embodiment, the blade angle 508 is approximately 145°. The actual blade angle varies based on the precision of the machining process that produces the knife and sharpens the blade. The blade angle may vary from 145° by, for example, +/−5° in some instances. Such a tolerance is implied when describing the approximate angle of the knife blade. Therefore, the stated blade angle is generally considered to be a mean or average value for the blade angle.

The angled cutting edge 502 concentrates the force applied by the knife 500 to a single location on a pipe. As such, the knife 500 is able to split or penetrate the pipe more quickly than a knife having, for example, a straight cutting edge. Additionally, a blade angle of approximately 145° substantially reduces the pipe deformation which occurs during a cut. For example, testing has shown that a knife having a blade angle of 145° produces a pipe deformation of 4 mm-5 mm before the pipe splits, and applies a force of approximately 4,500 N to the pipe (based on a torque of approximately 195 N·m generated by the pipe cutter). In contrast, a straight cutting edge produces a pipe deformation of 11 mm-12 mm before the pipe splits. The reduction in pipe deformation and increased concentration of applied force to the pipe before splitting also makes the blade angle of approximately 145° effective during low-temperature conditions to prevent the pipe from cracking, or the cut from burring. Also, although not specifically illustrated in FIG. 14, the cutting edge 502 is ground and polished to reduce the friction between the blade and the pipe. The reduced friction provides an additional reduction in the potential of a burred cut or pipe deformation.

Other embodiments of the invention include knives having angled blades with angles other than 145°. For example, knives 600, 700, and 800 illustrated in FIGS. 15-17, respectively, have similar characteristics to the blade 500 described above. Each knife increases the force applied to a single location on the pipe to cause the pipe to split more quickly, and reduces the amount of pipe deformation caused by the pipe cutter, when compared to knives that have a straight cutting edge.

FIG. 15 illustrates the knife 600 including an angled blade or cutting edge 602. The blade 602 has a first edge portion 604 and a second edge portion 606. The first edge portion 604 has a length L₁, and the second edge portion 606 has a length L₂. In the illustrated embodiment, the length L₁ of the first edge portion 604 is greater than the length L₂ of the second edge portion 606. In other embodiments, the first edge portion 604 and the second edge portion 606 have the same length, or the length L₂ of the second edge portion 606 is greater than the length L₁ of the first edge portion 604. The first edge portion 604 and the second edge portion 606 are oblique with respect to one another, or have an included blade angle 608 between them. In the illustrated embodiment, the blade angle 608 is approximately 135°. The 135° blade angle produced a pipe deformation of approximately 3 mm-4 mm.

FIG. 16 illustrates the knife 700 including an angled blade or cutting edge 702. The blade 702 has a first edge portion 704 and a second edge portion 706. The first edge portion 704 has a length L₁, and the second edge portion 706 has a length L₂. In the illustrated embodiment, the length L₁ of the first edge portion 704 is greater than the length L₂ of the second edge portion 706. In other embodiments, the first edge portion 704 and the second edge portion 706 have the same length, or the length L₂ of the second edge portion 706 is greater than the length L₁ of the first edge portion 704. The first edge portion 704 and the second edge portion 706 are oblique with respect to one another, or have an included blade angle 708 between them. In the illustrated embodiment, the blade angle 708 is approximately 155°. The 155° blade angle produced a pipe deformation of approximately 7 mm-8 mm.

FIG. 17 illustrates the knife 800 including an angled blade or cutting edge 802. The blade 802 has a first edge portion 804 and a second edge portion 806. The first edge portion 804 has a length L₁, and the second edge portion 806 has a length L₂. In the illustrated embodiment, the length L₁ of the first edge portion 804 is greater than the length L₂ of the second edge portion 806. In other embodiments, the first edge portion 804 and the second edge portion 806 have the same length, or the length L₂ of the second edge portion 806 is greater than the length L₁ of the first edge portion 804. The first edge portion 804 and the second edge portion 806 are oblique with respect to one another, or have an included blade angle 808 between them. In the illustrated embodiment, the blade angle 808 is approximately 165°. The 165° blade angle produced a pipe deformation of approximately 9 mm-10 mm.

In some embodiments, the pipe cutters described above may include a controller for executing control processes that further improve the performance of the pipe cutters. For example, the pipe cutters may include a controller and control process such as that illustrated and described in International Patent Application Publication No. WO______, entitled “PIPE CUTTER”, filed Sep. 1, 2009 (Attorney Docket No. 066042-9915-WO03), the entire contents of which is hereby incorporated by reference.

Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described. Various features and advantages are set forth in the following claims. 

What is claimed is:
 1. A power tool comprising: a pipe holder; a knife pivotally coupled to the pipe holder, the knife including a cutting edge having a first portion, a second portion, and an included angle between the first portion and the second portion, wherein the first portion of the cutting edge has a first length and the second portion of the cutting edge has a second length; a drive mechanism coupled to at least one of the pipe holder and the knife, the drive mechanism operable to move the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife; a motor coupled to the drive mechanism; and a power supply electrically coupled to the motor to selectively power the motor for operating the drive mechanism.
 2. The power tool of claim 1, wherein the angle is an obtuse angle.
 3. The power tool of claim 1, wherein the angle is between approximately 135 degrees and approximately 165 degrees.
 4. The power tool of claim 1, wherein the angle is approximately 145 degrees.
 5. The power tool of claim 1, wherein the angle is selected to minimize a deformation of a pipe.
 6. The power tool of claim 1, wherein the first length is greater than the second length.
 7. The power tool of claim 1, wherein the drive mechanism includes a gear assembly coupled to the at least one of the pipe holder and the knife to move the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife.
 8. A power tool comprising: a housing assembly supporting a motor and a drive mechanism; a pipe holder coupled to the housing assembly, the pipe holder configured to support a pipe; a knife pivotally coupled to the pipe holder, the knife including a cutting edge having a first portion, a second portion, and an included angle between the first portion and the second portion, wherein the first portion of the cutting edge has a first length and the second portion of the cutting edge has a second length; and a battery coupled to the housing assembly, the battery electrically coupled to the motor to selectively power the motor to drive the drive mechanism, the drive mechanism operable to move the knife relative to the pipe holder to cut the pipe supported by the pipe holder.
 9. The power tool of claim 8, wherein the angle is an obtuse angle.
 10. The power tool of claim 8, wherein the angle is between approximately 135 degrees and approximately 165 degrees.
 11. The power tool of claim 8, wherein the angle is approximately 145 degrees.
 12. The power tool of claim 8, wherein the angle is selected to minimize a deformation of a pipe.
 13. The power tool of claim 8, wherein the first length is greater than the second length.
 14. The power tool of claim 8, wherein the drive mechanism includes a gear assembly coupled to the knife to move the knife relative to the pipe holder.
 15. A pipe cutter comprising: a housing assembly; a pipe holder coupled to the housing assembly; a knife pivotally coupled to the pipe holder, the knife including a cutting edge having a first portion, a second portion, and an included angle between the first portion and the second portion, wherein the first portion of the cutting edge has a first length and the second portion of the cutting edge has a second length; and wherein the knife and the pipe holder defining a slot therebetween for receiving a pipe; a drive mechanism positioned at least partially within the housing assembly and coupled to at least one of the pipe holder and the knife, the drive mechanism operable to move the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife to cut the pipe positioned within the slot; a motor positioned at least partially within the housing assembly and coupled to the drive mechanism; and a battery pack removably coupled to the housing assembly, the battery pack electrically coupled to the motor to selectively power the motor to operate the drive mechanism for moving the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife
 16. The power tool of claim 15, wherein the angle is an obtuse angle.
 17. The power tool of claim 15, wherein the angle is between approximately 135 degrees and approximately 165 degrees.
 18. The power tool of claim 15, wherein the angle is approximately 145 degrees.
 19. The power tool of claim 15, wherein the angle is selected to minimize a deformation of a pipe.
 20. The power tool of claim 15, wherein the first length is greater than the second length.
 21. The pipe cutter of claim 15, wherein the drive mechanism includes a switch coupled to the pipe holder, and wherein a portion of the switch is operable to engage a portion of the knife to adjust the size of the slot.
 22. The pipe cutter of claim 15, wherein the battery pack is a Lithium-ion based battery pack.
 23. The pipe cutter of claim 15, wherein the battery pack is a power tool battery pack usable with the pipe cutter and another power tool.
 24. A power tool comprising: a pipe holder; a knife pivotally coupled to the pipe holder, the knife including a cutting edge having a first portion and a second portion, wherein the first portion of the cutting edge and the second portion of the cutting edge are oblique with respect to one another, and wherein the first portion of the cutting edge has a first length and the second portion of the cutting edge has a second length; a drive mechanism coupled to at least one of the pipe holder and the knife, the drive mechanism operable to move the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife; a motor coupled to the drive mechanism; and a power supply electrically coupled to the motor to selectively power the motor for operating the drive mechanism.
 25. The power tool of claim 24, wherein the first portion of the cutting edge and the second portion of the cutting edge have an included angle between them.
 26. The power tool of claim 25, wherein the angle is an obtuse angle.
 27. The power tool of claim 25, wherein the angle is between approximately 135 degrees and approximately 165 degrees.
 28. The power tool of claim 25, wherein the angle is approximately 145 degrees.
 29. The power tool of claim 25, wherein the angle is selected to minimize a deformation of a pipe.
 30. The power tool of claim 24, wherein the first length is greater than the second length.
 31. The power tool of claim 24, wherein the drive mechanism includes a gear assembly coupled to the at least one of the pipe holder and the knife to move the at least one of the pipe holder and the knife relative to the other of the pipe holder and the knife. 